What can the presence of protostars in a cloud indicate?

The presence of protostars in a cloud indicates that active star formation is occurring in the region. Protostars are in the early stages of stellar development, forming from the gravitational collapse of gas and dust within a molecular cloud. As these materials come together, they heat up and eventually lead to the formation of stars.

When astronomers observe protostars, it signifies that the cloud is not only dense enough for star formation but also that the processes involved in creating new stars are currently underway. This activity is a key aspect of cosmic evolution, as it contributes to the birth of new stars and the ongoing cycle of star formation and evolution in the universe.

In contrast to the presence of protostars, a transition to the red giant phase refers to a more evolved stellar stage that does not involve star formation. The idea of decaying molecular clouds being present does not directly relate to the formation of protostars, as such clouds may indicate a lack of active star formation. Lastly, the concept of halted stellar evolution would imply that no new stars are forming, which contradicts the very nature of protostars indicating ongoing star formation.